Istanbul University Faculty of Science

SOLAR OBSERVATIONS

Istanbul University Observatory · Sunspot observations since 1950

Observatory

Solar Images Monday, 21 April 2025

‹ 18.04.2025 2025 22.04.2025 ›

Photosphere sunspot drawing and RDS evaluation

21.04.2025 photosphere drawing

High-resolution scan (3230 px)

Time
08:30 UT
Observer
Korhan YELKENCİ
g
8
f
63
R
143
Seeing
3 / 5

Sunspot groups and observation details →

Sunspot groups (from the drawing)

Group 1 · AX_ – 3Group 1 · AX_ – 3 Group 2 · CAI – 7Group 2 · CAI – 7 Group 3 · DAI – 20Group 3 · DAI – 20 Group 4 · DAI – 23Group 4 · DAI – 23 Group 5 · AX_ – 1Group 5 · AX_ – 1 Group 6 · CAI – 4Group 6 · CAI – 4 Group 7 · HS_ – 1Group 7 · HS_ – 1 Group 8 · CAI – 4Group 8 · CAI – 4
RDS data file (.gzd) 
[Gözlem]
Tarih=21.04.2025
Saat=08:30
Gözlemci=Korhan YELKENCİ
KontrolEden=Olcay PLEVNE
Durumaçısı=-25.46
Enlemaçısı=-5.09
Boylamaçısı=62.46
Boylamfark=2
GKalite=3
GDurum=K.T
Kuzeyaçısı=-0.5
Sırano=20228
AyRasatNo=12
RasatÖnceki=18.04.2025
RasatSonraki=22.04.2025

[Leke Grupları]
Grupsayısı=8:3:5
LekeSayısı=63:30:33
RölatifSayı=143:60:83
01=AX_ 03 +07.267 +71.780 133.538 +0.000 0000 0 +07.766 +71.602 +06.767 +70.554 +07.267 +71.804 +07.267 +71.756
02=CAI 07 +04.275 +52.563 115.230 35.191 0000 0 +05.810 +54.658 +02.741 +50.469 +05.610 +54.458 +02.941 +50.669
03=DAI 20 +09.556 -17.360 045.424 19.440 0000 0 +11.605 -11.440 +07.507 -22.631 +11.405 -11.640 +07.707 -22.431
04=DAI 23 -02.661 +06.931 069.391 44.210 0000 0 -00.990 +09.621 -05.223 +04.241 -00.299 +09.347 -05.230 +04.441
05=AX_ 01 -03.620 -19.539 042.921 -1.000 0000 0 -03.620 -19.539 -03.620 -19.539
06=CAI 04 -30.169 -21.600 040.860 38.134 0000 0 -28.512 -19.542 -31.826 -23.659 -28.712 -19.742 -31.626 -23.459
07=HS_ 01 -04.346 -28.443 034.170 +0.000 0000 0 -03.797 -27.880 -04.896 -29.700 -04.346 -28.330 -04.346 -28.853
08=CAI 04 -25.834 -69.759 352.701 34.150 0000 0 -24.450 -67.856 -27.218 -71.661 -24.658 -67.943 -27.580 -71.410
20250421.gzd

Chromosphere (H-α) FITS frames

H-α

The images are made automatically with a fixed, gentle rule: uneven illumination and most of the limb darkening are removed, and the brightness is shown on a linear scale (no sharpening); prominences get their own scale outside the limb. Frames are ordered by sharpness (seeing); frames without the Sun (darks, bias) come last. Method →

2025/20250413_ky · KY · 14 frames · 18.8 MB · 08:10:47–08:13:08 UT

08:12:47 UT · 70 ms · over-exposed 08:11:31 UT · 70 ms · over-exposed 08:12:25 UT · 50 ms · over-exposed 08:12:03 UT · 30 ms · over-exposed 08:12:58 UT · 70 ms 08:12:36 UT · 50 ms 08:12:14 UT · 30 ms 08:13:08 UT 08:11:09 UT · 50 ms · over-exposed 08:10:47 UT · 30 ms · over-exposed 08:11:42 UT · 70 ms 08:11:20 UT · 50 ms 08:10:58 UT · 30 ms 08:11:52 UT

Coronado H-α animations from frame sequences

No Coronado observation for this day.